1. Field
The present embodiments relate to batteries for portable electronic devices. More specifically, the present embodiments relate to techniques for managing the use of high-voltage lithium-polymer batteries with portable electronic devices.
2. Related Art
Portable electronic devices, such as laptop computers, portable media players, and/or mobile phones, typically operate using a rechargeable battery. Furthermore, designs for such batteries often include battery packs that contain battery cells connected together in various series and parallel configurations. For example, a six-cell battery pack of lithium-polymer cells may be configured in a three in series, two in parallel (3s2p) configuration. Hence, if a single cell can provide a maximum of 3 amps with a voltage ranging from 2.7 volts to 4.2 volts, then the entire battery pack can have a voltage range of 8.1 volts to 12.6 volts and provide 6 amps of current. The charge in such batteries is typically managed by a circuit, which is commonly known as a protection circuit module (PCM) and/or battery management unit (BMU).
During operation, the battery's capacity may diminish over time from an increase in internal impedance, electrode and/or electrolyte degradation, excessive heat, and/or abnormal use. For example, oxidation of electrolyte and/or degradation of cathode and anode material within a battery may be caused by repeated charge-discharge cycles and/or age, which in turn may cause a gradual reduction in the battery's capacity. As the battery continues to age and degrade, the capacity's rate of reduction may increase, particularly if the battery is continuously charged at a high charge voltage.
Continued use of a lithium-polymer battery over time may also produce swelling in the battery's cells and eventually cause the battery to exceed the designated maximum physical dimensions of the device. Moreover, conventional battery-monitoring mechanisms may not include functionality to manage swelling of the battery. As a result, a user of the device may not be aware of the battery's swelling and/or degradation until the swelling results in physical damage to the device.
Hence, what is needed is a mechanism for mitigating swelling and/or degradation in high-voltage lithium-polymer batteries for portable electronic devices.